Avalanche Forecast

Issued: Jan 2nd, 2015 8:02AM

The alpine rating is considerable, the treeline rating is moderate, and the below treeline rating is moderate. Known problems include Wind Slabs and Persistent Slabs.

Avalanche Canada swerner, Avalanche Canada

Cautious route-finding and conservative decision making are essential. Wind slabs may dig deeper and fail on the persistent weak layer below.

Summary

Confidence

Poor - Wind effect is extremely variable on Saturday

Weather Forecast

Synopisis: On Saturday, the low off the North Coast will have weakened sufficiently, however unsettled conditions will exist with cloudy skies and light snow. Ridgetop winds will be moderate from the northwest. The next low pressure system will affect the Interior late Sunday afternoon and persist through Tuesday. However; models show the arctic air invading the South Rockies and Lizard Range before then, which will send temperatures plummeting and likely keep the moist air out. Snow amounts will be light 5-10 cm overnight Sunday and into Monday. Ridgetop winds will be strong from the northwest and treeline temperatures will hover near -15. Freezing levels will be at valley bottom through Monday, then rising Tuesday

Avalanche Summary

No new avalanches have been reported.

Snowpack Summary

Snow surfaces are variable with northerly, wind exposed aspects showing firm wind press or scoured exposed crust, and more sheltered locations have up to 30 cm of low density, faceted snow. In the alpine and at treeline, strong northerly winds have transported this snow into stiff and reactive wind slabs on opposite slopes. Up to 70 cm below the surface you will likely find a hard, thick crust which formed mid-December. At higher elevations this crust has facets (sugary) snow above it and well-preserved surface hoar up to 10 mm in size in sheltered locations at treeline and below. Where the crust exists, it may be bridging triggers from penetrating to deeper persistent weaknesses. However, on high alpine slopes above where the rain crust formed, or in areas where rain didn't occur, deeply buried facets may still be susceptible to triggering, especially in thinner snowpack areas.

Problems

Wind Slabs

An icon showing Wind Slabs
Between 15 and 30 cm of low-density snow has been transported by strong swirling winds into hard wind slabs. Initially winds blew from the NW and have now switched to the ESE, which means wind slabs are likely found in unsuspecting places.
Whumpfing, shooting cracks and recent avalanches are all strong inicators of unstable snowpack.>Use ridges or ribs to avoid pockets of wind loaded snow.>Avoid cross loaded features.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible - Likely

Expected Size

1 - 3

Persistent Slabs

An icon showing Persistent Slabs
A buried surface hoar/ facet/ crust interface is buried 70 cm down. Dig down and test weak layers and watch for this condition as you transition from treeline and above. Conservative terrain selection required.
Stick to well supported terrain and be aware of what is above you at all times.>Make observations and assess conditions continually as you travel.>

Aspects: All aspects.

Elevations: All elevations.

Likelihood

Possible

Expected Size

2 - 5

Valid until: Jan 3rd, 2015 2:00PM